Magnesioaubertite is a rare, water-soluble hydrous sulfate mineral typically found as a secondary mineral in mine dumps. It is easily identified by its characteristic pale blue color and its association with other secondary sulfate minerals in hyper-arid climates.

Hardness

2-3

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrareAubertite Group family

Magnesioaubertite

Hardness: 2-3
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this magnesioaubertite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch magnesioaubertite with a known reference. Magnesioaubertite sits at Mohs 2-3, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: white.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
4
Match the color range
Compare against the expected color range: blue.
5
Look at form & habit
Crystal system: triclinic. Typical habit: tabular crystals, crusts, efflorescences.

Often confused with

Magnesioaubertite vs. its common look-alikes, and how to tell them apart in the field.

mineral

Aubertite

Mohs 2-3

How to tell apart: Streak differs, so Magnesioaubertite leaves white, Aubertite leaves light blue.

Often found alongside magnesioaubertite

Minerals reported to co-occur with magnesioaubertite. Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: MgAl(SO₄)₂Cl·14H₂O
Mohs hardness: 2-3
Density: 1.80 g/cm³
Colors: Blue
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Triclinic
Crystal habit: Tabular crystals, crusts, efflorescences
Cleavage: On {010}, good
Rarity: Rare
Uses: Collector
Host rock: A rare secondary mineral formed by the reaction of volcanic gases and aluminum-bearing rocks

Where rockhounds find magnesioaubertite

Classic worldwide localities

Grotta de Faraglione and along the Baia de Levante, Vulcano, Lipari Islands, Italy

Field-hunting tip

Where it forms: A rare secondary mineral formed by the reaction of volcanic gases and aluminum-bearing rocks. If you start seeing alunogen, pickeringite, metasideronatrite in float, you are in the right ground. Typical habit: tabular crystals, crusts, efflorescences. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify magnesioaubertite?+

Mohs hardness is 2-3. Luster: vitreous. The streak is white. Common colors include blue.

Where is magnesioaubertite found?+

Notable localities include Grotta de Faraglione and along the Baia de Levante, Vulcano, Lipari Islands, Italy.

What rocks look like magnesioaubertite?+

Magnesioaubertite is most often confused with Aubertite, Chalcanthite, Pickeringite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with magnesioaubertite?+

Magnesioaubertite commonly co-occurs with Alunogen, Pickeringite, Metasideronatrite, Sulfur, Tamarugite, Aluminocopiapite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does magnesioaubertite form in?+

Where it forms: A rare secondary mineral formed by the reaction of volcanic gases and aluminum-bearing rocks. Working float back to the host body is the standard way to chase a fresh occurrence.

What is magnesioaubertite used for?+

Magnesioaubertite is used in collector.

Find magnesioaubertite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.